Nonsuicidal self-injury expectations and psychopathology over time: Linear and nonlinear multilevel modelling approaches

Nonsuicidal self-injury (NSSI), the deliberate self-infliction of tissue damage, is a serious behaviour with a host of negative consequences that has a considerable impact on the health system. People engage in NSSI for a variety of reasons and often expect desirable outcomes from NSSI (e.g., relieving emotions, communicating to or influencing others). Understanding the link between these expectations and various symptoms of psychopathology will help to refine theoretical models of NSSI and inform treatment. Female participants (N = 197) with a recent history of NSSI completed online measures of self-injury, psychopathology and psychological distress (including suicidality and depressive symptoms), and social support at 3-month time points for 24 months. Multilevel regression analyses of these time series data indicated that suicidality and depressive symptoms were positively associated with greater endorsement of intrapersonal NSSI expectations concurrently, and that depression positively predicted intrapersonal NSSI expectations at the following 3-month time point. Depressive symptoms were associated with interpersonal NSSI expectations concurrently but not prospectively. Overall, these findings further validate models of NSSI that distinguish between intrapersonal and interpersonal expectations within a longitudinal framework and suggests applications relevant to person-centred case conceptualizations of NSSI and NSSI treatment.